How to make the shading the same across all faces?
You can do this by connecting the image texture without a shader. In the image below, the rocks in the foreground (the ones on the right) are connected through a traditional Principled BSDF, whereas, the ones in the background (the un-shaded ones) are connected as shown. You will have to control the brightness and whatnot manually (if needed) using Bright/Contrast Nodes, or ColorRamps, however, as these are completely un-shaded. You can still give the objects a bit of a &quot;shadow effect&quot; if you want by turning on Ambient Occlusion.